9-(4-Aminophenyl polymethine)-9-xanthenol compounds and pressure sensitive system therewith

ABSTRACT

WHEREIN EACH R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3. These compounds are initially substantially colorless and are capable of becoming highly colored when brought into reactive contact with many conventional Lewis acid materials and the like. Accordingly these compounds are highly useful as a component of pressure-sensitive copying papers.   Disclosed are normally substantially colorless chromogenic 9-(4aminophenyl polymethine)-9-xanthenol color precursor compounds having the following structural formula:

United States Patent [1 1 Alsop [451 Dec. 30, 1975 [75] Inventor: Derek J. Alsop, North Tonawanda,

[7 3] Assignee: Moore Business Forms, Inc.,

Niagara Falls, N.Y.

22 Filed: Nov. 21, 1974 211 Appl. No.: 525,988

[52] U.S. Cl. 428/411; 260/240 D; 260/335; 427/151; 428/323 [51] Int. Cl. ..l C071) 311/90; C08K 5/15 [58] Field of Search 260/240 D, 335, 345.2; 427/151; 428/411, 323

[56] References Cited UNITED STATES PATENTS 3,192,204 6/1965 Craig et a1. 260/345.2 X 3,463,655 8/1969 lmamiya et al. 428/411 3,492,295 1/1970 Sureau et al 260/345.2 X 3,641,011 2/1972 Lin et al. 260/240 G 3,832,212 8/1974 Jenkins et al. 428/411 FOREIGN PATENTS OR APPLICATIONS 563,541 6/1958 Belgium 260/335 Primary Examiner-Allen B. Curtis [57] ABSTRACT Disclosed are normally substantially colorless chromogenic 9-(4-aminophenyl polymethine)-9-xanthenol color precursor compounds having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3. These compounds are initially substantially colorless and are capable of becoming highly colored when brought into reactive contact with many conventional Lewis acid materials and the like. Accordingly these compounds are highly usefulas a component of pressure-sensitive copying papers.

10 Claims, N0 Drawings 9-(4-AMINOPIIENYL POLYMETHINE)-9-XANTHENOL COMPOUNDS AND PRESSURE SENSITIVE SYSTEM THEREWITII BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to initially colorless chromogenic, color precursor compounds having particular utility in the field of carbonless copying. The compounds of the present invention may be utilized, for example, in the production of self-marking impact papers of the transfer or manifolding type wherein a first marking ingredient is carried on one sheet of paper for reaction with a second marking ingredient normally carried on a mating sheet of paper. Specifically the invention relates to a family of chromogenic 9-(4- aminophenyl polymethine)-9-xanthenol color precursor compounds having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3.

2. Description Of The Prior Art Impact or pressure sensitive carbonless transfer papers have recently come into wide usage in the United States and throughout the world. Ordinarily, such papers are printed and collated into manifolded sets capable of producing multiple copies. In this connection, pressure applied to the top sheet causes a corresponding mark on each of the other sheets of the manifolded set.

The top sheet of paper, upon which the impact or pressure is immediately applied, ordinarily has its back surface coated with microscopic capsules containing one of the reactive ingredients which produces a mark. A receiver sheet, placed in contact with such back face of the top sheet has its front surface coated with a material having a component reactive with the contents of the capsules so that when capsules are ruptured upon impact by stylus or machine key, the initially colorless or substantially colorless contents of the ruptured capsules react with a coreactant therefor on the receiver sheet and a mark forms on the receiver sheet corresponding to the mark impressed by the stylus or machine key.

In the art, impact transfer papers are designated by the terms CB, CFB and CF, which stand respectively for coated back, coated front and back" and coated front." Thus, the CB sheet is usually the top sheet and the one on which the impact impression is directly made; the CFB sheets are the intermediate sheets, each of which have a mark formed on the front surface thereof and each of which also transmits the contents of ruptured capsules from its back surface to the front of the next succeeding sheet; and the CF sheet is the last sheet and is only coated on its front surface to have an image formed thereon. The CF sheet is not 2 normally coated on its back surface as no further transfer is desired.

While it is customary to coat the capsules on the back surface and to coat the co-reactant for the capsules contents on the front surface of each sheet. this procedure could be reversed if desired. Further, with some systems, coatings need not be used at all and the coreactive ingredients may be carried in the sheets themselves, or one may be carried in one of the sheets and the other may be carried as a surface coating. Further, the reactantsmay both comprise microencapsulated liquids. Patents illustrative of many of the various kinds of systems which may incorporate such co-reactive ingredients and which may be used in the production of manifolded transfer papers include, for example, US. Pat. No. 2,299,694 to Green, US. Pat. No. 2,712,507 to Green, US. Pat. No. 3,016,308 to Macaulay, US. Pat. No. 3,429,827 to Ruus and US. Pat. No. 3,720,534 to Macaulay et al.

The most common variety of carbonless impact transfer paper, and the type with which the compounds of the present invention are preferably utilized, is the type illustrated, for example, in Green (U.S. Pat. No. 2,712,507) and Macaulay (U.S. Pat. No. 3,016,308) wherein microscopic capsules containing a liquid fill comprising a solution of an initially colorless chemically reactivecolor forming dye precursor are coated on the back surface of the sheet, and a dry coating of a co-reactant chemical for the dye precursor is coated on the front surface of a receiving sheet.

Many color precursors useful in connection with carbonless copying systems are known to those skilled in the art to which the present invention pertains. For example, specific reference is made to the color precursors mentioned in the patent to Phillips, Jr. et al, US. Pat. No. 3,455,721 and particularly to those listed in the paragraph bridging columns 5 and 6 thereof. Other color precursors are disclosed in US. Pat. No. 3,703,397 and US. Pat. No. 3,713,863 to Lin et al. These color precursor materials are capable of reacting with a CF coatingcontaining an acidic material such as the acid-leached bentonite-type clay disclosed in application Ser. No. 125,075 to Baxter filed Mar. 17, 1971, the entirety of which is hereby specifically incorporated by reference, or the acid-reactant organic polymeric material disclosed in the Phillips, Jr. et al US. Pat. No. 3,455,721.

Many of the color precursors disclosed in the patents referred to above, are capable of undergoing an acidbase type reaction with an acidic material. Other previously known color precursors are the spiro-dipyran compounds disclosed in the patent to I-Iarbort, US. Pat. No. 3,293,060 with specific reference being made to the disclosure of the US. Pat. No. 3,293,060 extending from column 11, line 32 through column 12, line 21. The color precursors disclosed in the patents listed above are initially generally colorless and capable of becoming highly colored when brought into contact with an acidic layer such as an acid-leached bentonitetype clay or an acid-reacting polymeric material, or the like.

Generally speaking, the color precursor materials disclosed above are dissolved in a solvent and the solution is encapsulated in accordance with the procedures and processes described and disclosed by Macaulay (US. Pat. No. 3,016,308) and by Green (US. Pat. No. 3,712,507) as mentioned above. Other processes for encapsulating color precursors are disclosed in US.

Pat. No. 3,429,827 to Ruus and US. Pat. No. 3,578,605 to Baxter. In this connection, it should be mentioned that the exact nature of the capsule itself is not critical as long as the same is capable of containing the color precursor and can be ruptured by the application of pressure in accordance with conventional carbonless copying procedures. Solvents known to be useful in connection with dissolving color precursors include chlorinated biphenyls, vegetable oils (castor oil, coconut oil, cotton seed oil, etc.), esters (dibutyl adipate, dibutyl phthalate, butyl benzyl adipate, benzyl octyl adipate, tricresyl phosphate, trioctyl phosphate, etc.), petroleum derivatives (petroleum spirits, kerosene, mineral oils, etc.), aromatic solvents (benzene, toluene, etc.), silicone oils, or combinations of the foregoing. Particularly useful are the alkylated naphthalene solvents disclosed in US. Pat. No. 3,805,463 to Konishi et a].

For a disclosure of acidic coatings which are capable of converting the color precursors into their highly colored form, reference is made to the disclosures of US. Pat. No. 3,622,364, US. Pat. No. 3,330,722, US.

Pat. No. 3,389,007 and US. Pat. No. 3,293,060, as well as to the disclosure of Baxter, application Ser. No. 125,075 referred to above.

In the color forming systems outlined above, as will be appreciated by those skilled in the art, the color precursors are conventionally contained in pressure rupturable microcapsules which are included in the back coatings of the sheets of carbonless copying manifolded sets. Further, it will be appreciated that the acidic coatings are generally utilized as front coatings with the color precursor material in a solvent therefor being transferred from an adjacent back coating to the acidic layer front coating upon rupture of the capsules which contain the color precursor material.

SUMMARY OF THE INVENTION HO/ CH c Ho \CH= CHQNfZ 4 contact with a color-activating material to yield vividly colored reaction products in areas where marking is desired.

It is another object of this invention to provide chr0- mogenic compounds which are substantially colorless or only slightly colored offering a new and improved variety of chromogenic characteristics and yielding novel vividly colored substances upon contact with color-activating materials.

It is a further object of this invention to provide new and improved, normally substantially colorless, chromogenic substances yielding colored reaction products when placed in reactive contact with Lewis acid materials.

The foregoing objects are achieved by the provision of a family of substantially colorless chromogenic 9-(4- aminophenyl polymethine)-9-xanthenol color precursor compounds having a structural formula as set forth above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a family of normally substantially colorless chromogenic 9-(4- aminophenyl polymethine)-9-xanthenol color precursor compounds having a structural formula as set forth above. These compounds are initially substantially colorless; however, when brought into contact with a solid Lewis acid electron acceptor material such as the acidleached bentonite-type clay disclosed in the application of Baxter, Ser. No. 125,075, they may be converted into a highly colored form. Various other solid acidic materials which are generally capable of converting these compounds into their highly colored form are disclosed in U.S. Pat. No. 3,622,364, US. Pat. No. 3,330,722, US. Pat. No. 3,389,007 and US. Pat. No. 3,293,060 referred to above.

The xanthenol compounds of the present invention wherein n 1 may be prepared by reacting one mol of a p-amino benzaldehyde compound with 9-methyl-9- xanthenol in the presence of HCl and thereafter neutralizing the reaction product with a base in accordance with the following formula:

Clem-Q8! ar 9-methyl-9-xanthenol may be prepared by treating xanthone with a Grignard reagent comprising magnesium and methyl iodide in accordance with the following reaction: (10 a A p-aminobenzaldehyde compound may be used in accordance with the foregoing to produce compounds of the present invention wherein n 1. For compounds wherein n 2, a 3-(p-aminophenyl) propenal compound having the formula H H H N C '-'-C C O may be used and for n =3, a 5-(p-aminophenyl) pentadienal compound having the formula may be used inlieu of the p-aminobenzaldehyde. In each of the foregoing formulas, R is as described above.

EXAMPLE I 30 grams (approximately 0.15 mole) of xanthone were dissolved in 250 ml of boiling benzene in 'a 1000 ml 2 neck boiling flask fitted with a condenser and a drying tube. After the xanthone was completely dissolved in the benzene, a Grignard reagent consisting of 12 grams (approximately 0.5 mole) of magnesium and 66 grams (approximately 0.47 mole) of methyl iodide was gradually added to the solution along with 100 ml of anhydrous diethyl ether. The solution immediately became orange and a yellow'solid separated. This yellow solid was rapidly reabsorbed, however, and later a colorless crystalline compound separated from the greyish-green liquid. The reaction mixture was then refluxed using a heating mantle for about 60 minutes and then all'of the ether and abouthalf of the benzene were removed. The solid was filtered off from the cold solution, washed with dry ether and dissolved in cold water. The yellow solution so formed was repeatedly extracted with ether until the aqueous layergave only a pale yellow color on the addition of concentrated hydrochloric acid. The resultant ethereal solution was dried with Na SO and the ether was evaporated using a steam bath to present 16.0 grams (approximately 0.075 mole) of a deep yellow, gummy, partially crystalline product which was 9-methyl-9-xanthenol.

EXAMPLE [I 6 glacial acetic acid and then HCl gas was bubbled through the resultant solution for about 10 minutes until the color of the solution had become intensely red-brown. This red-brown solution was poured into I O 1) (I C I: 0)

Ho cH 2000 ml of water to present an intensely blue solution of the dye. A very pale lime green precipitate was formed by neutralizing the blue solution with an aqueous 15% NH, solution and this precipitate was filtered, washed and dried to present 8.2 grams of a 9-(4-dimethylamino phenyl polymethine)-9-xanthenol compound having the following structural formula:

- c ,CH

Ho \CH=CH-N 3 CH3 EXAMPLE lll 1.00 gm of the xanthenol product produced in accordance with Example 11 was admixed with 20.0 grams of R-lOO solvent (a commercial product of Kureha Corporation of America which is a mixture of alkylated naphthalenes and is apparently generally disclosed in U.S. Pat. No. 3,806,463 to Konishi et al.) and this admixture was warmed slightly on a hot plate until a clear solution (solution A) was obtained. Thereafter solution A was allowed to cool to room temperature. (When a small quantity of solution A was applied to an acid-leached clay coating on a paper substrate, a vivid blue color appeared.) Then, 3.26 gms of terephthaloyl chloride were added to 10.0 gms of R-lOO solvent and this mixture was also warmed slightly on a hot plate until a clear solution (solution B) was obtained. Solution B was then allowed to cool to room temperature. After solutions A and B were prepared, gms of an aqueous solution containing 2.0 weight percent Elvanol 50-42 (a commercial product of E. l. duPont de Nemours which is a polyvinyl alcohol with 87 to 89% hydrolysis and a viscosity of 35 to 45 cps in a 4% aqueous solution at 20C) were placed in a semi-micro Waring blender and then solutions A and B were mixed together at room temperature and the resultant solution was added to the Elvanol solution in the blender. The blender was activated and high shear agitation was continued for about 2 minutes until an emulsion having a dispersed phase particle size of about 2 to 10 microns was obtained. In this emulsion, the aqueous solution containing the Elvanol polyvinyl alcohol formed the continuous phase and the solution containing the R- l 00 solvent, the 9-(4-dimethyl-aminophenyl polymethine)-9-xanthenol and terephthaloyl chloride formed the dispersed phase. The emulsion was then transferred to a suitable container such as a beaker and was stirred with a variable speed mechanical stirrer t 300 to 500 7 rpm while an aqueous solution containing L86 gms of diethylene triamine, 1.20 gms of sodium carbonate and ml of water was added. Stirring was continued at room temperature for about 24 hours until a stable pH of about 8.0 was observed. At this time, the particles of dispersed phase had become individually encapsulated in a polyamide shell. The slurry containing the microcapsules and having the Elvanol polyvinyl alcohol binder in the continuous phase was then drawn down on a 13 pound neutral base continuous bond paper sheet at a coating weight of approximately 2.34 to 3.04 gms per square meter and the coated sheet was oven dried at a temperature of 110C for about to 45 seconds. The dry coating on the paper sheet was slight yellow. The dry coating of microcapsules containing the 9-(4-dimethylaminophenyl polymethine)-9-xanthenol compound was then brought into contact with an acid-leached clay coating on the surface of another sheet of paper and when an impression was made on the reverse side of the sheet coated with microcapsules a corresponding blue colored reproduction of such impression appeared on the acid-leached clay coating 'within approximately 30 seconds.

EXAMPLE IV In this Example, the procedures and quantities of materials were identical with Example 111, except that in this instance, dibutyl phthalate was utilized as the solvent for the dispersed phase rather than R-lOO. The results were identical with those obtained in Example 111.

While the foregoing Examples specifically disclose the production and use of a 9-(4-dimethylaminophenyl polymethine)-9-xanthenol compound of the present invention wherein n 1, it is pointed out that the present invention also contemplates and specifically encompasses the similar production and use of 9-(4- aminophenyl polymethine)-9-xanthenol compounds as generally disclosed above wherein the amino nitrogen atom carries either hydrogen atoms, methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups or any mixture of two of the foregoing and wherein n l, 2 or 3. Moreover, other solvents for color precursors are known to those skilled in the art to which this invention pertains and any solvent which does not substantiallyinterfere with the formulation of color when the color precursor is contacted with a co-reactant may be utilized.

It is also to be noted that the compounds of the present invention are useful generally in the production and generation of colored marks and it is not critical to the present invention that the same be utilized in a copying system or in a microencapsulated form.

I claim:

1. A 9-(4-aminophenyl polymethine)-9-xanthenol compound having the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms and wherein n is an integer from 1 to 3.

2. A compound as set forth in claim 1 having the following structural formula:

CH HO/ CH=CH 3 NCH3 3. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a p-aminobenzaldehyde compound with one molar equivalent of 9-methyl-9-xanthenol.

4. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a 3-(p-aminophenyl) propenal compound with one molar equivalent of 9-methyl9-xanthenol.

5. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a S-(p-aminophenyl) pentadienal compound with one molar equivalent of 9-methyl-9-xanthenol.

6. A method as set forth in claim 3 wherein said p-aminobcnzaldehyde compound is p-dimethylaminobenzaldehyde.

7. In a pressure-sensitive recording system comprising a layer of microcapsules containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim 1.

8. In a pressure-sensitive recording system comprising a layer of microcapsules containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim 2.

9. In a pressure-sensitive recording system comprising a'layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim 1.

10. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim 2. 

1. A 9-(4-AMINOPHENYL POLYMETHINE)-9XANTHENOL COMPOUND HAVING THE FOLLOWING STRUCTURAL FORMULA:
 2. A compound as set forth in claim 1 having the following structural formula:
 3. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a p-aminobenzaldehyde compound with one molar equivalent of 9-methyl-9-xanthenol.
 4. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a 3-(p-aminophenyl) propenal compound with one molar equivalent of 9-methyl-9-xanthenol.
 5. A method for preparing a xanthenol compound as set forth in claim 1 comprising reacting one molar equivalent of a 5-(p-aminophenyl) pentadienal compound with one molar equivalent of 9-methyl-9-xanthenol.
 6. A method as set forth in claim 3 wherein said p-aminobenzaldehyde compound is p-dimethylaminobenzaldehyde.
 7. IN A PRESSURE-SENSITIVE RECORDING SYSTEM COMPRISING A LAYER OF MICROCAPSULES CONTAINING A SUBSTANTIALLY COLORLESS COLOR PRECURSOR COMPOUND AND A LAYER OF AN ELECTRON-ACCEPTOR MATERIAL, THE IMPROVEMENT WHICH COMPRISES UTILIZING, AS SAID COLOR PRECURSOR COMPOUND, A XANTHENOL COMPOUND AS SET FORTH IN CLAIM
 1. 8. In a pressure-sensitive recording system comprising a layer of microcapsules containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim
 2. 9. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim
 1. 10. In a pressure-sensitive recording system comprising a layer containing a substantially colorless color precursor compound and a layer of an electron-acceptor material, the improvement which comprises utilizing, as said color precursor compound, a xanthenol compound as set forth in claim
 2. 